The React SDK has been rewritten from the ground up and is built on the new JavaScript Client SDK (@launchdarkly/js-client-sdk).

Highlights:

• Modern React support. Built with modern React design patterns in mind and fully compatible with the latest React (19).
• Better maintainability. We've relocated the React SDK source into our js-core monorepo so it stays in sync with our other JavaScript SDKs.
• Better security. The package has been renamed to @launchdarkly/react-sdk, making it a scoped package.
• React Server Components support. A new LDIsomorphicProvider (server) + LDIsomorphicClientProvider (client) pair lets you evaluate flags on the server and seamlessly hydrate on the client — no waterfalls, no loading flash. First-class support for the Next.js App Router.
• Server-side flag evaluation. The new createLDServerSession() API binds a server client to a context per request, with request-scoped memoization via React cache(). Use any evaluation variant directly inside RSCs.

Docs